I am a serious novice at c# and need help

i have this script to allow me to click on an object, get a message, and click again to close it. i need to somehow fit a command in it to change the GUIStyle. here is my script, anyone who could fill in the command i need would be my new best friend.

 using UnityEngine;
 using System.Collections;
 
 class ShowTextButton1 : MonoBehaviour
 {
     public string title = string.Empty;
     private bool showText = false;
     public Texture2D background;
     private GUIStyle style = null;
     private void InitStyle()
     {
         if (style != null) return;
         style = new GUIStyle(GUI.skin.button);
         if (background != null) style.normal.background = background;
     }
 
     void OnMouseDown()
     {
         if(!showText)
             showText = true;
     }
     
     void OnGUI()
     {
         if(showText)
         {
             if(GUI.Button(new Rect(100,170,400,60), title))
 
                 showText = false;
         }
     }
 }